- When waitress receives a ``Transfer-Encoding: chunked`` request, we no longer
  send the ``TRANSFER_ENCODING`` nor the ``HTTP_TRANSFER_ENCODING`` value to
  the application in the environment.  Instead, we pop this header.  Since we
  cope with chunked requests by buffering the data in the server, we also know
  when a chunked request has ended, and therefore we know the content length.
  We set the content-length header in the environment, such that applications
  effectively never know the original request was a T-E: chunked request; it
  will appear to them as if the request is a non-chunked request with an
  accurate content-length.

- Cope with the fact that the ``Transfer-Encoding`` value is case-insensitive.

Fixes #43